The present invention relates, in general, to measuring fluid, and more particularly to estimating the height or quantity of a fluid in a mixing tank while reducing noise due to internal and external forces. More specifically, the invention relates to methods and systems for estimating in real time the height and volume of a fluid contained in a mixing tank.
There exist several methods of measuring quantity or height of a fluid in a mixing tank such as a metering rod or gauge. But these traditional methods are inherently inaccurate due to measurement inaccuracies, precision errors, and achievable resolution.
The use of tank fluid height sensing in a mixing process is important in controlling the mixing capacity and preventing the system from overflowing. Most of the current measuring systems use devices such as height sensors to obtain direct measurement of the height or quantity of a fluid in a mixing tank. Height sensors inherently capture the effects of noise in the system as well as noise created by the sensor itself. In order to obtain the most accurate measurement of the height or quantity of fluid in the mixing tank, it is advantageous to remove the effects of this noise.
In situations where the tank is in motion, such as those found in a ship based mixing system, it is also advantageous to remove the height oscillations in the measurements. Some existing systems mitigate the mixing level oscillations and the sensor noises by employing two or more sensors and computing the average of the measurements in the hopes of removing the measurement errors.
It is apparent from the foregoing that a reliable method and an appropriate implementing apparatus are needed. Such method and apparatus are expected not only to perform the measurements but also to derive with more accuracy from these measurements an estimation of the quantity or the height of a fluid placed in a mixing container to avoid having the mixing container overfilled.
Moreover, changes in the quantity or the height of the fluid needs to be monitored in real time with more precision especially when the fluid properties are also subject to internal forces such as inertial and pressure forces.
Therefore, there is a need to develop improved method and apparatus for measuring and estimating the quantity or the height of a fluid in a mixing tank that is affected not only by external but also by internal forces. The estimation or control of such measurements should remove the effects of inherent height sensor noise as well as noise in the system created by internal and external forces that could affect the readings of the height of the mixing fluid.